Ductless or Ducted Fumehood with Improved Front Sash Closure

This patent application claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 63/658, 048, filed Jun. 10, 2024 by FIPAK Research And Development Company and Stephane Hauville et al. for ALTERNATIVE NOVEL SASH WITH MOVABLE CLOSURE (Attorney's Docket No. FIPAK-35 PROV), which patent application is hereby incorporated herein by reference.

This invention relates to air filtration systems in general, and more particularly to fumehoods comprising a front opening configured to selectively enclose a workspace such that the workspace is isolated (or substantially isolated) from the ambient air, whereby to allow dangerous substances to be safely handled in the enclosed workspace without endangering nearby personnel.

Air filtration systems are used in many situations to purge unwanted substances from the air. Such air filtration systems generally exist in a variety of forms, depending upon their use and function.

One type of air filtration system is the fumehood. Fumehoods provide an enclosed workspace which is isolated (or substantially isolated) from the ambient air in order to allow dangerous substances to be safely handled in the enclosed workspace without endangering nearby personnel. As used herein, the term “fumehood” is intended to encompass any enclosed space configured for working with hazardous materials or agents which utilizes negative air pressure to protect an operator from the materials or agents being manipulated in the enclosed space. By way of example but not limitation, the term “fumehood” as used herein encompasses “fume cupboard”, “chemical hood”, “exhaust hood”, “laboratory hood”, “ventilation hood”, “ducted hood”, “ductless fume hood”, “safety hood”, “containment hood”, “airflow hood”, etc.

Fumehoods are generally either ducted or ductless. Ducted fumehoods are configured to purge hazardous substances from the air of the enclosed workspace before venting that air to the ambient atmosphere. Ductless fumehoods are configured to purge hazardous substances from the air of the enclosed workspace before venting that air to the ambient air of the room containing the ductless fumehood.

The present invention is applicable to both ducted and ductless fumehoods. For purposes of illustration but not limitation, the present invention will now be discussed in the context of ductless fumehoods.

More particularly, and looking now at, there is shown a typical prior art ductless fumehood. Ductless fumehoodgenerally comprises an enclosed workspacedefined by a frameand accessed by a front sash closure, with front sash closureengaging a workbasewhen the enclosed workspace is “sealed”. An air inletadmits ambient air into enclosed workspace, and an air ventremoves air from enclosed workspace. Air from air ventis passed through a filterbefore being returned to the ambient air of the room (e.g., a laboratory) containing ductless fumehoodvia an air outlet. Filterremoves hazardous substances from the air, thereby rendering the air safe before it is returned to the ambient air. An outlet fanis generally provided between air ventand air outletso as to keep enclosed workspaceat a negative pressure differential relative to the ambient air, whereby to ensure that any air within enclosed workspacepasses through filterbefore being returned to the ambient air. A sensoris generally provided at (or downstream of) filterso as to ensure that the filter purges any hazardous substances from the workspace air before that air is returned to the ambient air. Outlet fanand sensorare generally connected to an alarmwhich can alert personnel in the event that filter, outlet fanand/or sensorfail.

Ductless fumehoods have become popular due to their technical effectiveness, low acquisition and implementation costs, rapid installation and substantial energy savings. More particularly, with proper filter selection, ductless fumehoods can be extremely effective in removing hazardous substances from the air of a workspace. Furthermore, due to their simple design and their ductless nature, ductless fumehoods are relatively inexpensive to manufacture and relatively inexpensive to implement, since they do not require the extensive engineering and installation efforts normally associated with ducted fumehoods. Furthermore, installation of ductless fumehoods is fast and simple, since ductless fumehoods require little more than uncrating and initial setup and testing before use. Ductless fumehoods are also extremely energy efficient, since they return the filtered air to the ambient air of the room rather than venting the filtered air to the outside atmosphere. As a result, already-heated air is retained in the room during winter and already-cooled air is retained in the room during summer, thereby minimizing the energy required to temperature-condition the air in the room.

With ductless fumehoods, it is important to manage the airflow out of enclosed workspacein order to ensure that all hazardous substances are removed from the workspace air before it is allowed to return to the ambient air of the room. Ideally, this means that all of the enclosed workspace air is passed through filterbefore that air is allowed to return to the ambient air of the room. In practice, however, this is difficult to ensure, inasmuch as personnel must typically repeatedly and actively access enclosed workspacethrough front sash closure, and hence some air from the enclosed workspace may pass into the air of the room via the open front sash closurewithout first passing through filter. To limit this occurrence, and as previously discussed, outlet fanis set to keep enclosed workspaceat a negative pressure differential relative to the ambient air, whereby to minimize unintentional airflow out open front sash closure. In addition, front sash closureis typically arranged so as to minimize the size of the opening provided into enclosed workspace.

More particularly, and looking now at, front sash closuretypically comprises a plurality of interconnected sliding panes. When enclosed workspaceis to be accessed by personnel, the bottommost paneis lifted upwards, causing the interconnected sliding panesto overlap in a cascading fashion whereby to progressively expose more and more of the enclosed workspace to the personnel. Thus, a conventional front sash closureprovides a variable-sized opening into enclosed workspace, with the variable-sized opening enlarging upward “from the bottom up”.

While conventional front sash closuresof the sort shown inhave proven highly effective and highly reliable, they can also provide a sub-optimal solution in certain situations. More particularly, as noted above, conventional front sash closuresopen “from the bottom up”. Thus, in situations where the objects to be manipulated (e.g., test tubes, beakers, etc.) sit directly on workbaseand are relatively short, the “bottom up” closure of conventional front sash closureneed only expose a relatively small region of enclosed workspacein order to provide the personnel with appropriate access to the objects which are to be manipulated. However, in situations where the objects to be manipulated sit elevated above workbase(e.g., on a stand or pole) and/or are relatively tall, the “bottom up” closure of conventional front sash closurerequires that a relatively large region of enclosed workspacebe exposed in order to provide the personnel with appropriate access to the objects which are to be manipulated. However, it will be appreciated that this is a sub-optimal solution, since it increases the possibility that hazardous substances may escape from enclosed workspacethrough the open front sash closure. Moreover, with prior art fumehoods utilizing a conventional front sash closure, either the entire horizontal dimension of workspaceis closed off (i.e., front sash closureis in the fully-down position), or the entire horizontal dimension of workspaceis fully accessible (i.e., front sash closureis disposed in any partially-up position, exposing the entire horizontal dimension of workspacefrom the left side of workpieceto the right side of workspace). Stated somewhat differently, with the front sash closureof prior art fumehoods, it is not possible to provide an opening into workspacehaving a horizontal dimension that is smaller than the horizontal dimension of front sash closure.

It should also be appreciated that front sash closurecomprising the aforementioned cascading sliding panesmay result in a situation in which the sliding panes can fall down unexpectedly if inadvertently un-latched, creating a potentially dangerous situation for the user. And, there may be situations in which the user wishes to entirely remove a portion of the front sash closure(e.g., one or more of the cascading sliding panes) which is not possible with prior art fumehoods utilizing cascading sliding panes.

It should also be appreciated that, with prior art fumehoods utilizing a “bottom up” type front sash closure(e.g., one or more cascading sliding panes), upward movement of the panes of the front sash closure requires that the user lift the panes against the force of Earth's gravity, and such panes may be large and heavy depending on the materials utilized and the size/height of the fumehood. To counteract this, it is common in the art to employ counterweights (e.g., disposed in frame) which are connected to the upper portion of front sash closure(or the upper portion of the sliding panesthereof) via cabling. Such a construction reduces the force that the user must exert to move the panes upward (i.e., by virtue of the fact that the counterweights act to assist the user in raising the panes upward), however, such a construction requires cables and pulleys disposed in framethat can be points of failure (e.g., cabling frays and eventually breaks) requiring expensive repairs or replacement.

It will be appreciated that the same issues can arise with respect to ducted fumehoods which use a conventional front sash closurecomprising the aforementioned cascading sliding panes.

Thus there is a need for an improved front sash closure for a ductless fumehood, and/or a ducted fumehood, which, (i) permits a user to close-off the bottom-most portion of the front opening of a fumehood while maintaining an opening for accessing the workspace intermediate the top and bottom of the front of the fumehood, (ii) permits the user to configure the fumehood such that the central opening for accessing the workspace comprises a horizontal dimension that is less than the horizontal dimension of the workspace, (iii) permits the front closure to be locked in an upward position, (iv) permits a portion of the front closure of the fumehood to be entirely removed from the fumehood, and (v) eliminates the complex counterweights utilized in prior art fumehoods.

The present invention comprises the provision and use of an improved front sash closure for a ductless fumehood, and/or a ducted fumehood, which, among other things, (i) permits a user to close-off the bottom-most portion of the front opening of a fumehood while maintaining an opening for accessing the workspace intermediate the top and bottom of the front of the fumehood, (ii) permits the user to configure the fumehood such that the central opening for accessing the workspace comprises a horizontal dimension that is less than the horizontal dimension of the workspace, (iii) permits the front closure to be locked in an upward position, (iv) permits a portion of the front closure of the fumehood to be entirely removed from the fumehood, and (v) eliminates the complex counterweights utilized in prior art fumehoods.

In one preferred form of the present invention, there is provided a front closure for a fumehood comprising a workspace defined by a frame, the front closure comprising:

In another preferred form of the present invention, there is provided a fumehood comprising:

In another preferred form of the present invention, there is provided a method for handling hazardous substances, the method comprising:

The present invention comprises the provision and use of an improved front sash closure for a ductless fumehood, and/or a ducted fumehood, which (i) permits a user to close-off the bottom-most portion of the front opening of a fumehood while maintaining an opening for accessing the workspace intermediate the top and bottom of the front of the fumehood, (ii) permits the user to configure the fumehood such that the central opening for accessing the workspace comprises a horizontal dimension that is less than the horizontal dimension of the workspace, (iii) permits the front closure to be locked in an upward position, (iv) permits a portion of the front closure of the fumehood to be entirely removed from the fumehood, and (v) eliminates the complex counterweights utilized in prior art fumehoods.

In one preferred embodiment of the invention, and looking now at, there is shown a novel ductless fumehood.

Novel ductless fumehoodis generally similar to ductless fumehooddiscussed above, however, with novel ductless fumehood, front sash closureis replaced by a novel front closure.

Novel front closuregenerally comprises a transparent arcuate panehaving a central openingformed therein, and a movable panethat is configured to be selectively moved relative to arcuate pane, and which is configured to be selectively removeable from fumehood, as will hereinafter be discussed in further detail.

More particularly, and looking now at, fumehoodgenerally comprises a framedefined by a back surface, an upper surface, and a pair of side surfaces. Arcuate paneis mounted to framesuch that frameand arcuate panetogether enclose and define a workspacecomprising a workspace surface. Arcuate paneis preferably mounted to framevia one or more hinge(s)() extending across a horizontal dimension of the fumehood so as to permit arcuate paneto be rotated upward so as to access the entirety of workspace(e.g., for cleaning workspaceand/or arcuate pane, etc.).

Central openingin arcuate paneis formed such that central openingextends from workspace surface(i.e., the lowermost edge of arcuate pane) up to a location between the lowermost edge of arcuate paneand the uppermost edge of arcuate pane(e.g., the midpoint). As a result of this construction, a person seeking to manipulate objects inside workspace(e.g., scientific apparatus, chemicals, biological material, etc.) can reach through central openingwith their hands while standing outside of fumehood.

However, it has been recognized that in some circumstances, it is desirable to selectively close-off a portion of central openingin order to facilitate safe handling of objects inside workspace. By way of example but not limitation, it has been recognized that in some circumstances, it is desirable to partially cover the lower portion (e.g., the lower half) of central openingwhile manipulating objects inside workspaceso as to provide additional protection to the person standing outside of fumehood. Specifically, it has been recognized that maintaining negative air pressure inside the fumehood (i.e., in the workspace) is desirable because such negative air pressure ensures that hazardous fumes, etc., flow up and into the outlet of the fumehood where they are directed to a filter system or ducting to an area of safe release to atmosphere. Thus, it is important to maintain negative air pressure flow in workspace, ensuring that hazardous fumes, etc., cannot exit workspacevia opening(thereby protecting the user standing just in front of openingoutside of the fumehood). It will be appreciated that one way to ensure negative pressure inside workspace, and hence air flow from the region outside of fumehoodand into central opening, is to reduce the total size of opening. Thus, movable paneserves two related protective functions: movable pane(i) protects the user from possible “splashing” and spills of materials contained within workspaceby providing a physical barrier, and (ii) protects the user from possible escape of hazardous fumes, etc., from workspacevia central openingby reducing the total open area of central openingand thereby facilitating the maintaining of negative air pressure within workspace.

To that end, movable paneis configured to be selectively mounted to (or removed from) fumehood, as will hereinafter be discussed in further detail.

More particularly, and looking now at, movable panecomprises a front panehaving a front surfaceand a rear surface. It will be appreciated that front panemay comprise a transparent material (e.g., plexiglass or similar) of the type that will be apparent to one of skill in the art in view of the present disclosure. A pair of handlesare mounted to front surfaceof front paneso as to permit a user to grasp movable paneand selectively mount (or remove) movable paneto (or from) fumehoodand/or move movable panebetween a lower position and an upper position, as will hereinafter be discussed in further detail.

A pair of guidesare mounted to rear surfaceof front paneof movable paneso as to be disposed generally perpendicular thereto. Each of guidescomprises an outboard surfacewhich faces side surfaceof framewhen movable paneis mounted to frame, and an inboard surfacewhich faces central openingwhen movable paneis mounted to frame. See. Inboard surfaceof each guidecomprises at least one mounting pinextending laterally outboard (i.e., perpendicular) therefrom for facilitating mounting of movable paneto frame, as will hereinafter be discussed in further detail. In one preferred embodiment of the invention, inboard surfaceand/or outboard surfaceof each guidecomprises a plurality of bearing elements(e.g., ball bearings retained with a collet so as to rotate freely within the collet) for facilitating smooth movement of movable panerelative to framewhen mounted thereto, as will be apparent to one of skill in the art in view of the present disclosure.

Each guidefurther comprises an upper surfacedisposed between, and extending perpendicular to, outboard surfaceand inboard surfaceof each guide. Upper surfaceof each guidepreferably comprises a magnetic clasp() for mating with and selectively magnetically mounting movable paneto a ferrous metal counterpart of frame, as will hereinafter be discussed in further detail.

Looking now at, a pair of mounting bracketsare mounted to each of side surfacesof frameof fumehoodon the inner surface thereof. Each mounting bracketcomprises an outboard platecomprising a central recessed region, an inboard platecomprising a generally T-shaped cutoutformed on the surface thereof that faces central recessed regionof outboard plate, and a spacer platedisposed between outboard plateand inboard plate. A ferrous metal retainer bracketis mounted to spacer platesuch that a ferrous metal portion of bracketis disposed at the uppermost region of T-shaped cutout, whereby to receive and magnetically mount to magnetic claspof each guide, as will hereinafter be discussed in further detail.

Looking now at, when outboard plate, spacer plateand inboard plateare mounted together so as to form mounting brackets, central recessed regionof outboard plateand T-shaped cutoutof inboard plate, spaced away from one another via spacer plate, present a generally T-shaped groove. T-shaped groovecomprises a first extension, a downwardly-extending second extensiondisposed generally perpendicular to, and opening on, first extension, and an upwardly-extending third extensiondisposed generally perpendicular to, and opening on, first extension.

Mounting pinsof guidesof movable paneare sized to be received in T-shaped groove, whereby to permit movable paneto be mounted to mounting brackets, and hence to frame, so as to selectively close off an upper portion or a lower portion of central opening, as will hereinafter be discussed in further detail.

More particularly, a user may mount movable paneto fumehoodso as to close off a portion of central openingby grasping movable paneby handles, and then moving movable panesuch that mounting pinsare aligned with first extensionof T-shaped groove(). The user can then move movable panetowards arcuate paneso that mounting pinsare received in first extensionof T-shaped groove. Once mounting pinshave been advanced along first extensionto the location at which third extensionof T-shaped grooveintersects with first extension, the user can move movable paneupward so as to move mounting pinsinto third extension, and the user can move movable paneupwards until magnetic claspon upper surfaceof each guideof movable panemagnetically engages, and mounts to, ferrous metal retainer bracketof each respective mounting bracket. Once magnetic claspis mounted to ferrous metal retainer bracket, movable paneis mounted to framein the upper-most position (), permitting direct access to workspace surfacevia central opening. It is important to note that if the user were to release hold of handlesafter mounting movable panein its upper-most position, movable panewould remain locked to framein its upper-most position, whereby to close off the upper portion of central opening, but permit hands-free direct access to workspace surfacevia central opening.

It should be appreciated that it is possible to move movable panefrom its upper-most position to its lower-most position so as to permit direct access to an upper portion of workspacevia central opening. Specifically, once movable paneis disposed in its upper-most position (as shown in) so as to be magnetically mounted to ferrous metal retainer bracketsin the manner discussed above, the user can slide movable panedownward such that mounting pinsmove along third extension(e.g., by applying sufficient downward force to movable paneto disengage the magnetic connection between magnetic claspand ferrous metal retainer brackets) and then continue sliding movable panedownward such that mounting pinscontinue into second extensionuntil movable paneis disposed in its lower-most position. T-shaped grooveis formed such that when the user releases hold of handlesafter moving movable paneto its lower-most position, movable pane, under the power of Earth's gravity, remains disposed at a location that closes off the lower portion of central opening, but still permits access to an upper portion of workspace. See.

It should be appreciated that T-shaped grooveis formed to have a size and geometry that facilitates the mounting of movable paneto framein a manner which closes off the upper portion of central openingwhen movable paneis mounted to framein its upper-most position while still permitting access to workspace surface, and which closes off the lower portion of central openingwhen movable paneis mounted to framein its lower-most position while still permitting access to an upper portion of workspace.

It should also be appreciated that movable paneof the present invention is also constructed such that movable panecan be entirely removed from fumehood(whereby to leave central openingof arcuate paneunobstructed). More particularly, and looking now at, if desired, the user can move movable panein the manner discussed above such that mounting pinsof movable paneare disposed in alignment with first extensionof T-shaped groove. The user can then pull handlesof movable paneso as to move mounting pinsinto first extension, continuing to pull movable paneaway from arcuate paneuntil movable paneis completely removed from, and separated from, fumehood.

Finally, it should be appreciated that as movable paneis moved relative to arcuate panein the manner discussed above, guidesof movable paneare received in the gap between outboard plateand inboard plate(i.e., the gap defined by spacer plate). As this occurs, bearing elementsdisposed on outboard surfaceof guidesand/or inboard surfaceof guidesengage and roll along central recessed regionof outboard plateof mounting brackets, and T-shaped cutoutof inboard plateof mounting brackets, respectively. As a result of this construction, movable paneis able to move smoothly relative to arcuate paneand undesirable binding of mounting pinswithin T-shaped groovesis avoided.

It is also important to note that due to the shape of T-shaped groove, movable panemay not be removed, either accidentally, or on purpose, from framewhen movable paneis disposed in its upper-most position or its lower-most position.

Movable panemay only be mounted to, or removed from, frameby moving mounting pinsinto, and out of, first extensionof T-shaped groove.

It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.